Using N-Norms for Analyzing Symmetric Protective Electrical Circuits with Triple Modal Reservation

The redundancy of functional blocks and critical assemblies in radio-electronic equipment is among the most widely used techniques for increasing reliability. Complex redundant systems raise the problem of electromagnetic compatibility (EMC). Ignoring EMC requirements can lead to partial or complete REE failures. In this paper, the authors analyze a noise-protective electrical circuit with triple modal reservation (a promising type of cold redundancy). A multilayer stripline is investigated, the conductors of which are symmetrically arranged relative to two planes. On account of the strong electromagnetic coupling, this protective circuit can decompose dangerous ultra-wideband (UWB) interference received at the input of the primary or redundant circuits into unipolar pulses of lower amplitude. Using this approach, due to the symmetry of the conductors, equal decomposition efficiency could be achieved. However, the effect of UWB interference at the input of one of the conductors produces bipolar pulses at the output of the other conductors. In this paper, the authors evaluate the dangers of unipolar and bipolar decomposed pulses and use modal analysis to mathematically determine the polarities and amplitudes of the decomposed pulses at all output nodes for a pseudo-matched structure. By using the quasistatic approach with and without losses, the time responses to a trapezoidal pulse with a total duration of 60 ps, which simulates UWB interference, are obtained. To confirm the results of modal analysis and quasistatic simulation, an experimental study is performed. Using a stroboscopic oscilloscope DSA 8300, the authors obtained a transient response to a step excitation. Then, taking the derivative, the response to a trapezoidal pulse with a total duration of 140 ps was obtained. To analyze the criticality of the decomposed pulses, N-norms are used. In the general case, it is shown that the UWB interference is decomposed into four pulses of lower amplitude. At the same time, the value of each N-norm indicates its significant attenuation. For example, the amplitude of the UWB pulse acting on the input of the reserved conductor decreases by 10.31–8.93 times. Such results numerically demonstrate the high efficiency of the suggested approach when it comes to protecting equipment against UWB interference. It is also shown that the probability of dielectric breakdown and damage to electronic components in redundant circuits is lower than in a primary circuit. This is due to the fact that the value of N3 in the redundant circuit is 2.38 times less than in the primary circuit. However, the results demonstrate that arcing is highly probable both in primary and redundant circuits. Finally, aspects of symmetry/asymmetry in the problem under investigation are emphasized.

Implementation and Control of Six-Phase Induction Motor Driven by a Three-Phase Supply

This paper is interested in implementing and controlling a modified six-phase induction motor (MSPIM) when fed from a three-phase supply either via an inverter or with a direct grid connection loaded by a centrifugal pump. The main aims of using the MSPIM are to enhance motor reliability and reduce torque pulsation. A three-to-six phase transformer has been designed, implemented, and employed to enable the SPIM to be driven from a three-phase supply. It is preferable to use the three-to-six phase transformers integrated with three-phase inverter on using the six-phase inverter to generate lower values of harmonics and lower steady-state error of speed and reduce the starting current and because also it isolates the primary circuit from the secondary, and the cost will be lower compared to the design of a special six-phase inverter. Dynamic models of SPIM, three-to-six phase transformer, and three-phase variable speed drive are derived. Then, a scalar (V/F) closed-loop control of SPIM is employed, and the results are discussed. Fine-tuning of PID controllers is used to keep the motor speed tracking the reference value. A low pass filter is connected to reduce the ripple of voltage and current waveforms. An experimental setup has been built and implemented to check the possibility of controlling SPIM by a variable speed drive system fed from a three-to-six phase transformer. It is found that the proposed method can be effectively used to drive the SPIM from a three-phase supply.

Corrosion Behavior of Chromium Coated Zy-4 Cladding under CANDU Primary Circuit Conditions

The manuscript is focused on corrosion behavior of a Cr coating under CANada Deuterium Uranium(CANDU) primary circuit conditions. The Cr coating is obtained via the thermionic vacuum arc procedure on Zircaloy -4 cladding. The surface coating characterization was performed using metallographic analysis and scanning electron microscopy (SEM) with an energy dispersive spectra detector (EDS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) investigations. The thickness of the Cr coating determined from SEM images is around 500 nm layers After the autoclaving period, the thickness of the samples increased in time slowly. The kinetic of oxidation established a logarithmic oxidation law. The corrosion tests for various autoclaving periods of time include electrochemical impedance spectroscopy (EIS) and potentiodynamic tests, permitting computing porosity and efficiency of protection. All surface investigations sustain electrochemical results and promote the Cr coating on Zircaloy-4 alloy autoclaved for 3024 h as the best corrosion resistance based on decrease in corrosion current density values simultaneously with the increase of the time spent in autoclave. A slow increase of Vickers micro hardness was observed as a function of the autoclaved period as well. The value reached for 3024 h being 219 Kgf/mm2 compared with 210 Kgf/mm2 value before autoclaving.

Magnetic Coupling-Based Battery Impedance Measurement Method

The battery impedance is an important indicator of battery health status. In this paper, a magnetic coupling-based impedance measurement method for electrochemical batteries is proposed. Without affecting the energy injection stage, the designed suppression resistance can minimize the influence of the primary circuit response, and the under-damped oscillation waveform containing the battery impedance information can be directly obtained on the primary inductance. The change of the mutual inductance value within a certain range will not affect the measurement results. Therefore, the measurement system has high stability and robustness. By utilizing the discrete Fourier transform (DFT)-based algorithm to calculate the damped oscillation parameters, the battery impedance is accurately derived from the calculated attenuation coefficient and damped oscillation frequency. The accuracy of this method under different coupling parameters is analyzed and verified by simulation and experiment on a Li-ion battery, which could be employed to estimate the state of charge (SOC).

Development and verification of methods for predicting the frequency of self-oscillations in swirling coolant flows of nuclear power plants

Methods and algorithms for calculating the frequency of self-oscillations in swirling coolant flows of nuclear power plants with VVER reactors have been developed. The frequency of self-oscillations occurring in the acoustic sections of the primary circuit and their connections in the starting modes of the power unit and when operating at the rated power level is predicted. It is established that the self-oscillation frequencies can fall into the frequency bandwidth of mechanical vibrations and vibrations of the reactor plant’s internal devices. It is shown that in order to prevent the resonance of self-oscillations of the coolant with the vibration frequencies of internal devices, it is necessary and sufficient to take the frequency of self-oscillations outside the bandwidth of the vibration frequency of structures. The results of verification of the results of forecasting the frequency of self-oscillations in swirling coolant flows at a nuclear power plant unit with VVER are presented. The application of the developed technique shows that the pendulum oscillations of the VVER - 1200 body are caused by an increase in the parameters of the coolant and the geometric dimensions of the VVER - 1200 reactor compared to VVER-1000.

Prediction of Dissolved Impurities and Movement of Oxide Particles in the Primary Circuit of LBE Fast Reactor

To better understand the corrosion and corrosion products behavior in the primary circuit of lead-bismuth eutectic (LBE) coolant reactor, the concentration distribution of soluble impurities and the transport of solid particles are investigated through the finite-element method. An axisymmetric model of the primary circuit of an LBE reactor was constructed to accelerate the calculation of the thermal hydraulic filed of the circuit. The saturation concentration of solute Fe, Cr and Ni in LBE coolant are identified through the equilibrium of their oxides and PbO, and the very different saturation concentrations of Fe/Cr/Ni in LBE will lead to significant element-selective corrosion. The migration of solid oxide particles in the primary circuit is also investigated by the Euler–Lagrange tracing model. The simulation shows that driving force for the movement of particles >100 μm is buoyancy, which lets particles float on a free surface, while particles <10 μm tend to suspend in coolant. However, the behavior of particles also depends on the formation position, the particles formed above the core have a high possibility of re-entering in the core.

Prediction of Global Corrosion and Corrosion Products Behavior in the Primary Circuit of LBE Fast Reactor

For better understanding the corrosion and corrosion products behavior in the primary circuit of lead-bismuth eutectic (LBE) coolant reactor, the concentration distribution of soluble impurities and the transport of solid particles are investigated through finite-element method. An axisymmetric model of the primary circuit of LBE reactor was constructed to accelerate the calculation the thermal hydraulic filed of circuit. The saturation concentration of solute Fe, Cr and Ni in LBE coolant are identified through the equilibrium of their oxides and PbO. And the very different saturation concentrations of Fe/Cr/Ni in LBE will lead to significant element selective corrosion. The migration of solid oxides particles in the primary circuit is also investigated by the Euler-Lagrange tracing model. The simulation shows that driving force for the movement of particles &amp;gt;100 &mu;m is buoyancy, which lets particles float on a free surface, while particles &amp;lt;10 &mu;m tend to suspend in coolant. However, the behavior of particles also depends on the formation position, the particles formed above the core have the high possibility of re-entering in the core.

Developing an Algorithm for Determining Malfunctions in the Measuring Channels of the Acoustic Leak Control System

Nowadays Russian and foreign NPP operate systems for monitoring coolant leakage at the primary circuit based on measuring the dispersion of generated acoustic signals (acoustic waves) propagating over the metal surface. In the acoustic leak monitoring systems provision are made to self-diagnosis of measuring channels, as well as an adaptive algorithm is applied that allows automatic readjusting to the use of neighboring measuring channels instead of those that have failed. At the same time, there may be such malfunctions in the system technical means that do not automatically diagnose the malfunction of the measuring channels, which may lead to the failure of the system function to determine the magnitude and coordinate of the leak of the primary circuit coolant. That is why, the task of developing algorithms for determining the malfunction of the measuring channels of the acoustic leak monitoring system, implemented using software without making changes to the technical means of the system, is urgent. An algorithm is proposed for determining the malfunction of the measuring channels of the acoustic leak control system using a test signal of increased duration. An analysis of the applicability of the algorithm was performed on a representative sample of signals from measuring channels of the acoustic leak monitoring system of campaign 2018--2019 Novovoronezh NPP-2 рower Unit no. 1. The proposed algorithm has been implemented in the testing mode at power Unit no. 1 of Novovoronezh NPP-2 since the start of a new campaign in July 2019

Application of Artificial Intelligence for Automated Detection of Defects in Nuclear Energy Domain

Ensuring the integrity of the primary circuit in nuclear power plants is crucial considering the extreme pressures and temperatures while operating Pressurized Water Reactors (PWR). Non-Destructive Testing (NDT) on such harsh environments is a challenging and complex scenario. Automated assistance on acquisition and analysis systems can importantly contribute as supplementary safety barrier by providing real-time alarms for potential existence of defects. In this paper we present the application of Artificial Intelligence in Visual Testing (VT) of Bottom Mounted Nozzles (BMN) of the Reactor Pressure Vessel (RPV). The method that we apply is based on Object Detection using Convolutional Neural Networks (CNN) combined with the Transfer Learning technique in order to limit the necessary training time of the model and the use of Data Augmentation methods for reducing the size of the learning data set. The proposed CNN demonstrates great performances for automatic surface defect detection (cracks) in highly noisy environments with variating illumination conditions. These performances combined with accurate localization and characterization of the defects confirms the interest of advanced CNNs against traditional imaging processing methods for NDT applications. In this study, the results of a comparative blind-test between Human VT analysts are also presented.